1. Field Of The Invention
The present invention relates to a method of manufacturing integrated circuits and other electronic devices. More particularly, the invention relates to an improved apparatus and process for the etching of semiconductor materials.
2. Description Of The Related Art
Deposited films are used in the fabrication of VLSI circuits. These films must usually be patterned to provide the desired function. The patterning process can use a variety of well known pattern transfer methods (e.g. using a patterned mask to transfer an image to the deposited film). After the deposited film is covered with such a patterned mask (e.g. photoresist), the exposed portion of the deposited film can then be removed.
An etching process is generally used in semiconductor manufacture to remove exposed portions of the deposited film. One etching process that can be used to remove the exposed film is dry or plasma-assisted etching which use plasmas in the form of low pressure gaseous discharges. These etch processes provide high fidelity transfer of resist patterns.
In some instances, for example, when the deposited film can be damaged by a plasma generated within the process chamber or when greater control over anisotropy is desired, some of all of the etchant species can be activated outside of the process chamber. If additional excitation is required or desired it can be accomplished in the process chamber. When this excitation is provided outside the process chamber the process may be referred to as either afterglow, downstream or remote plasma etching.
Defects are caused by the presence of particulates on the surface of the processed materials. This was one of the reasons for the shift away from wet etches and to dry etches. Under certain conditions, however, remote plasma etchers can create particulates to be generated and carried to the surface with the etchant stream, thereby contaminating the surface of the processed material.
Remote plasma etchers generally activate the etchant by passing it through a microwave cavity. The process gasses, including the etchant, are flowed through a discharge tube formed from an insulating material (e.g. quartz) which passes through the microwave cavity. These activated process gasses in combination with the high temperatures in the discharge tube can etch the internal surfaces of the quartz discharge tube and the generated quartz particulate is passed in the process gas stream to the face of the surface to be processed.
These particulates are becoming more and more troublesome because of two trends in integrated circuit processing. First, as device dimensions become smaller and smaller, the size of a fatal defect becomes smaller, so that it is necessary to avoid the presence of smaller and smaller particles. Second, there is an increased desire to use large size integrated circuits.
Thus, there is a need for a remote plasma process that does not contaminate the surface being processed.